Reactive Oxygen Substances Research Articles

Melatonin reduces oxidative damage induced by aluminium in rat kidney

We evaluated the effect of melatonin (Mel), in male Wistar rats which received aluminium (Al) lactate for 12 weeks (0.57 mg Al/100 g body weight (b.w.), i.p. three times per week). Moreover rats received Mel (10 mg/kg b.w. i.p. 5 days/weeks) for 12 weeks. At the end of the treatment water and sodium balances were studied, and nephrogenic cyclic adenosine monophosphate (cAMP) was also measured. Urinary osmolality was measured after the administration of desmopressin (vasopressin agonist) to assess concentrating capacity. Oxidative stress in renal tissue and Na +–K +ATPase and gamma-glutamyl transferase (GGT) activities in whole plasma membrane were determined. Sodium and water balances were impaired by Al. We found decreased urinary concentrating ability and nephrogenic cAMP excretion. Al increased the Na +–K +ATPase activity, and serum aldosterone concentration. Mel normalized serum aldosterone level, the Na +–K +ATPase activity and potassium urinary without improving water and sodium excretion. Mel treatment did not improve the impaired urinary concentrating ability. Al reduced the GGT activity, an effect that persists in Al + Mel. Al exposure promoted oxidative stress with an increase in lipid peroxidation (LPO), and a decrease in glutathione (GSH) and glutathione peroxidase (GSH-Px) and catalase (CAT) activities. Mel markedly attenuated oxidative stress produced by Al. This may result from the higher efficacy of melatonin in scavenging various free radicals and also because of its ability in stimulating the antioxidant enzymes. However, it only reduced some alterations in the renal functions particularly related to the water and sodium excretion, which would be independent of the increased production of reactive oxygen substances.

Red blood cell glutathione peroxidase activity in female nulligravid and pregnant rats

BackgroundThe alterations of the glutathione peroxidase enzyme complex system occur in physiological conditions such as aging and oxidative stress consequent to strenuous exercise.MethodsAuthors optimize the spectrophotometric method to measure glutathione peroxidase activity in rat red blood cell membranes.ResultsThe optimization, when applied to age paired rats, both nulligravid and pregnant, shows that pregnancy induces, at seventeen d of pregnancy, an increase of both reactive oxygen substance concentration in red blood cells and membrane glutathione peroxidase activity.ConclusionThe glutathione peroxidase increase in erythrocyte membranes is induced by systemic oxidative stress long lasting rat pregnancy.

Influence of Various Antioxidants on Microscopic-Oxidative Stress Indicators and Fertilizing Ability of Frozen-Thawed Bull Semen

Cryopreservation is associated with the production of reactive oxygen substances (ROS), which lead to lipid peroxidation of sperm membranes, resulting in a loss of sperm motility, viability and fertility. The aim of this study was to determine effects of the antioxidants of oxidized glutathione (GSSG), reduced glutathione (GSH) and bovine serum albumin (BSA) on standard semen indicators (motility, acrosome and total abnormalities, HOST), endogenous antioxidant enzyme activities and fertilizing ability of frozen-thawed bull semen. Eighteen ejaculates from each of 3 Holstein bulls were collected using an artificial vagina and 9 replicates of the ejaculates were diluted with a Bioxcell®-based extender supplemented with antioxidants, including BSA (5 mg/ml), GSH (2 mM), GGSG (2 mM), and an extender containing no antioxidants (control). Insemination doses (1.5 × 107 sperm/0.25 ml straw) were prepared for the insemination of cows at observed oestrus. Supplementation with antioxidants led to lower percentages of acrosome damage (4.0 ± 0.5%, 4.4 ± 0.5%, 4.0 ± 0.3%, respectively) and total abnormalities (10.3 ± 0.7%, 9.7 ± 0.8%, 10.4 ± 0.6%), compared to the controls (6.5 ± 0.6 and 14.9 ± 1.1% P < 0.01). Pregnancy rate after insemination was highest (72.2%) in the group which was given BSA (P < 0.05). There were no significant differences among groups in GSH and glutathione peroxidase (GSH-PX) enzyme activities. Superoxide dismutase (SOD) activities (0.05 ± 0.005, 0.03 ± 0.005, 0.05 ± 0.009 μkat/g protein, respectively) in all of the experimental groups with antioxidants were lower than the control group (0.11 ± 0.024 μkat/g protein, P < 0.001). Furthermore, BSA increased (P < 0.001) the activity of catalase (CAT, 304.23 ± 114.69 μkat/g protein), following the freezing-thawing process.

Oxidant stress and cardiovascular absolute risk in Tunisian type 2 diabetes

cardiovascular diseases constitute the most hefty complications in diabetes. Absolute cardiovascular risk (ACVR) can be estimated by many equations that are continuously criticised. The aim is, in one hand, to evaluate ACVR in type 2 diabetes and, in the other hand, is to establish correlations between ACVR and oxidant-antioxidant status. 183 type 2 diabetes and 200 controls were admitted. ACVR assessment was calculated following Laurier equation. Oxidant status was evaluated by the measure of homocysteine, hydrogen peroxide (H2O2) and LDL thiobarbituric reactive oxygen substances (LDL-TBARS). Antioxidant status was evaluated by the measure of superoxide dismutase (SOD) activity, glutathione peroxidase (GPx), total antioxidant status (TAS) vitamins A, E and zinc. Glycated haemoglobin (HbA1c) and microalbuminuria were assessed by turbidimetry. ninety percent of diabetes belonged to moderate and high ACVR groups. In diabetic men ACVR was doubled each elevation of 4 micromol/L homocysteine, of 50 micromol/L of H2O2 and of 20 mg/L of microalbuminuria. High risk ACVR group showed the lowest SOD activity, zincemia and the highest HbA1c. No significant difference was found in LDL-TBARS, TAS, GPx, vitamins A, E between the different ACVR groups. The strong relation between homocysteine and ACVR confirms homocysteine atherosclerotic role. Homocysteine auto-oxidation produces H2O2 leading to LDL-TBARS increase. Microalbuminuria-ACVR association verifies its vasculopathy predictor role. Urinary albumin leakage may be consequent to the hyperhomocysteinemia found in diabetes. homocysteine introduction in ACVR assessment equation may ameliorate this estimation.

In vitro investigations for the QSAR mechanism of lymphocytes apoptosis induced by substituted aromatic toxicants

The objective of this study was to assess the chemicals-induced apoptosis effects on fish lymphocytes and to use the QSAR model to interpret the relationships between apoptotic effects and chemical structures to identify the immune toxicology mechanism. By the use of a simple in vitro toxicological assay, the measured apoptotic parameter (EC50) is used in a QSAR to interpret the apoptotic effects of 25 substituted benzenes at low exposure levels. The apoptotic effects of all tested substituted aromatic chemicals with Carassius auratus lymphocytes were confirmed by DNA ladder and nucleus condensation. For both chlorobenzenes and PCBs, the EC50 values increase with increasing Cl number in the molecule, a result reflecting probably the increased p–π conjugation of the C–Cl bonds that lowers the molecular reactivity. Furthermore, the apoptotic EC50 data were best correlated with the dipole moment ( μ) and the energy of the lowest unoccupied molecular orbital (ELUMO) such that: log ( 1 / EC 50 ) = 0.325 + 0.222 μ − 0.163 ( ELUMO ) (with R 2 = 0.879). The dependence on the electronic ELUMO factor of the established correlation suggests that during the apoptotic process the ROS (reactive oxygen substance) produced by cells acts as a Lewis base in substituted nucleophilic reactions with toxic chemicals behaving as an electron acceptor. On the basis of the test results, the present toxicological assay offers a rapid tool for assessing the toxic effects of chemicals at low exposure levels.

Concentration of Oxygenated Polycyclic Aromatic Hydrocarbons and Oxygen Free Radical Formation from Urban Particulate Matter

PM2.5 filter samples were collected in summer 2005 at an urban background site in Augsburg, Germany. They were analyzed for polycyclic aromatic hydrocarbons (PAH) and their oxygenated derivatives (O-PAH) using gas chromatography/mass spectrometry. Oxygen free radical formation (reactive oxygen substances, ROS) was measured by electron spin resonance (ESR) spectroscopy after addition of spin trapping agent directly on the same filters. The concentrations of ambient, high-boiling PAH and O-PAH were highly correlated to ROS formation, even better than to particulate mass or number concentration. Correlations were most pronounced for some polycyclic aromatic monoketones (e.g., benz[de]anthracene-7-one), which are not yet reported in literature to be redox cycling active. The association found between ESR measurements and the presence of specific semivolatile organic compounds suggests an important influence of wood burning in PM2.5-associated ROS formation. These results indicate that further research on the relationship between radical formation and presence of specific O-PAH and semivolatile organic compounds (SVOC) are likely to provide a better understanding of the relationship between the source-dependent chemical composition of PM and the toxicological risks associated with PM exposure.

音響外傷に関する最近の知見

Acoustic trauma remains a most important issue in technologically advanced countries. Overexposure to intense sound damages the inner ear sensory cells and can lead to temporary threshold shift (TTS) or permanent threshold shift (PTS) if exposure is sufficiently intense or prolonged. This review includes the recent findings of histological, metabolic, physiological changes after sound exposure and the proposed mechanisms for protection from acoustic injury.Cats, guinea pigs and mice are widely used as experimental models for hearing research. Recently, mice have been more frequently used because their genomic information and lower degree of inter-animal variability in the response to sound exposure. Overexposure damages the cochlea in two ways, i. e. mechanical and metabolic pathways. In mice, intense exposure (over 116dB SPL 2 hours, 8kHz octave band noise) simultaneously damages the organ of corti and stria vascularis by mostly mechanical pathways. However, sound exposure (112dB SPL 2 hours, 8kHz octave band noise) damaged the organ of Corti within a week by mechanical and metabolic pathways. The first row of outer hair cells is the most vulnerable to sound. Sound exposure (100dB SPL 2 hours, 8kHz octave band noise), which showed damage to only the first row of outer hair cells in histological findings, causes 40dB PTS.To prevent and protect PTS from sound exposure, some factors or reagents have been identified in animal models, 1) efferent reflex via the olivocochlear bundle (OCB); animals with a large OCB reflex are resistant to sound. 2) conditioning effect; “conditioning” the ear by pre-exposure to a moderate level, non-traumatic sound or heat stress, restraint can dramatically reduce the development of PTS by subsequent sound exposure. 3) Reactive oxygen substances (ROS) scavenger, glutathione; oxidative stress damages the tissue, while ROS scavenger can protect the ear from sound exposure. 4) blocker of glutamate, or neutrophine, 5) steroid. Some reagents have been examined in humans as clinical trial in the US.

The Relationship Between Lipid Peroxidation and LDL Desialylation in Experimental Atherosclerosis

ABSTRACTHigh serum total cholesterol concentration has been strongly connected with atherosclerosis in numerous studies. Being the main carrier of cholesterol in blood, low-density lipoprotein (LDL) is also the principal lipoprotein causing atherosclerosis. Sialic acids are a family of amino sugars that are commonly found as terminal oligosaccharide residues on glycoproteins and are sialylated on their apolipoprotein and glycolipid constituents. In several studies, it was demonstrated that LDL has a 2.5- to 5-fold lower content of sialic acid in patients with coronary artery disease compared with healthy subjects. The role of oxidatively modified LDL in the pathogenesis has been well documented. These studies have focused on modifications in the lipid and protein parts of LDL. But recently, desialylated LDL and its relation with the oxidation mechanisms have received attention in the pathogenesis of atherosclerosis and coronary artery disease (CAD). From these points, we have performed atheroma plaques in an experimental atherosclerosis model with rabbits and examined the LDL and plasma sialic acid and thiobarbituric acid reactive substance (TBARS) levels in the same model. We also have determined serum sialidase enzyme activities relevant with these parameters. LDL sialic acid levels were significantly decreased in the progression of the atherosclerosis (by the 30th, 60th, and 90th days). LDL and plasma TBARS levels and plasma sialidase enzyme activities were significantly elevated by the same time periods. In conclusion, serum sialidase enzyme may play an important role in the desialylation mechanism, and reactive oxygen substance (ROS) may affect this reaction.

Staphyloxanthin Plays a Role in the Fitness of Staphylococcus aureus and Its Ability To Cope with Oxidative Stress

Staphyloxanthin is a membrane-bound carotenoid of Staphylococcus aureus. Here we studied the interaction of staphyloxanthin with reactive oxygen substances (ROS) and showed by comparative analysis of the wild type (WT) and an isogenic crtM mutant that the WT is more resistant to hydrogen peroxide, superoxide radical, hydroxyl radical, hypochloride, and neutrophil killing.

Proliferating effects of the flavonoids daidzein and quercetin on cultured chicken primordial germ cells through antioxidant action

Primordial germ cells (PGCs) are undifferentiated pluripotent stem cells, whose proliferation is influenced by many internal and external factors. In the present study, a PGC-somatic cell co-culture model was established to evaluate effects of the flavonoids daidzein (DAI) and quercetin (QUE) on proliferation of PGCs from embryonic chickens. PGCs were isolated from the germinal ridge of 3.5-4day embryos and cultured in 5% fetal calf serum (FCS)-supplemented Medium 199. PGC subculture was carried out on chicken embryonic fibroblast feeder (CEF) or follicular granulosa cell feeder (GCF) layers. The subcultured PGCs were challenged with flavonoids alone or in combination with a reactive oxygen substance (ROS)-producing system on CEF for 48h. The results showed a better supporting effect of CEF than GCF. Flavonoids (1microg/ml) significantly promoted PGC proliferation, which could be markedly inhibited by ROS. The oxidative damage by ROS was further manifest by decreased superoxide dismutase activity and glutathione levels. In addition, activation of protein kinase A (PKA) by forskolin significantly stimulated PGC proliferation, but PKA inhibitor H89 inhibited the proliferating effects induced by DAI and QUE. These results indicated that cultured PGCs respond to exogenous agents on proliferation and that antioxidant flavonoids could restore the intracellular antioxidant system and promote PGC proliferation via their antioxidant action involving the PKA signaling pathway.

Evaluation of nitrosative and oxidative stress in Behçet disease

Plasma nitrotyrosine and nitrite/nitrate levels as markers of nitrosative stress and plasma malondialdehyde (MDA) and protein carbonyl as markers of oxidative stress were determined in patients with Behcet disease (BD). To evaluate the balance between oxidant and antioxidant systems in these patients, we measured erythrocyte lysate CuZn superoxide dismutase (CuZn SOD) activity, plasma sulfhydryl (SH) values and total antioxidant activity. We also determined levels of plasma C-reactive protein (CRP), a key marker of inflammation, and compared them with those of healthy subjects. We found plasma nitrotyrosine levels of BD patients to be increased, indicating that nitrosative stress may occur in these patients. Plasma MDA and CRP levels in BD patients were found to be significantly higher than those in control group. However, plasma SH levels were decreased. No changes were observed in the other measured parameters of the patient group compared with the controls. These data suggest the possible involvement of nitric oxide (NO) together with reactive oxygen substances (ROS) in the pathogenesis of BD.

EVALUATION OF ERYTHROCYTE Na+, K+ -ATPASE AND SUPEROXIDE DISMUTASE ACTIVITIES AND MALONDIALDEHYDE LEVEL ALTERATION IN COAL MINERS

The purpose of the present study was to determine the structural integrity of red blood cells in coal miners by assessing the concentration of malondialdehyde and the activities of superoxide dismutase and, Na + , K + -ATPase in erythrocytes. Occupational exposure to coal mine dust can result in a wide range of lung diseases, which include pneumoconiosis, bronchitis, and emphysema. Pathophysiological mechanisms of the diseases are not fully understood; however, cytotoxicity is related to reactive oxygen substances which are produced by coal dust. The study population consisted of 40 coal workers previously known not to have any pulmonary disease and 34 healthy subjects who were randomly selected from the population register or recruited from the hospital staff. The activities of Na + , K + -ATPase in the erythrocyte membrane was significantly decreased in the coal workers as compared to the control group. Serum potassium and iron concentrations were significantly higher whereas serum sodium was moderately decreased in coal workers as compared to control. MDA levels of all samples were significantly increased in the coal workers as compared to the control group. SOD activity in serum and erythrocyte was significantly lower in the coal miner group as compared to the control group. The present study demostrated that the elevated MDA and iron levels and insufficiency of antioxidant potential in serum and erythrocytes cause a decrease in erythrocyte Na + , K + -ATPase enzyme activity in coal

Application of near-infrared reflectance spectroscopy (NIRS) to the evaluation of carotenoids content in maize.

The importance of including antioxidant compounds in the diet is well recognized. These compounds remediate the detrimental activity on animal cells of the so-called reactive oxygen substances (ROS). Many papers have reported on the determination of both hydrophilic and hydrophobic antioxidant compounds present in a large number of vegetables, and all methods involve the extraction from the matrix of the compounds to be determined. Because some problems may arise, such as the completeness of the extraction and the stability of the extracted compound during the extraction steps, the possibility of analyzing these compounds in the native matrix would be useful. Here is reported the application of near-infrared spectroscopy (NIRS) to the determination of the content of carotenoids in maize, comparing the obtained data with those derived from high-performance liquid chromatography (HPLC) determination of the extract obtained from the same samples. Equations for predicting carotenoid content in maize were derived using scores from modified partial least-squares (MPLS) as independent variables. Cross-validation procedures indicated good correlations between HPLC values and NIRS estimates. The results show that NIRS, a well-established and widely applied technique, can be applied to determine the maize carotenoids and that samples are readily analyzed in minutes, the only required step being their grinding.

Protective effects of intraperitoneal vitamin C, aprotinin and melatonin administration on retinal edema during experimental uveitis in the guinea pig.

A considerable amount of clinical and experimental evidence exists suggesting the involvement of reactive oxygen substances (ROS) in the aetiology of uveitis. The activated phagocytic system of polymorphonuclear leucocytes in uveitis is involved in the generation of ROS. In addition to their direct free radical scavenging action, aprotinin, melatonin and vitamin C are known to protect against oedema formation and can preserve plasma membrane fluidity and free radical production. Histological changes in the retina that occur during uveitis are not well explained. The purpose of this study was to determine whether vitamin C, aprotinin and melatonin can protect the retina from damage accompanying experimental uveitis (EU). Thirty adult male guinea pigs were divided into five groups of six animals each. The first group was used as control. The right eyes of groups 2, 3, 4 and 5 received an intravitreal injection of bovine serum albumin for induction of experimental uveitis. At the same time and also on the consecutive third day, groups 3, 4 and 5 received intraperitoneal injections of vitamin C (ascorbic acid, 100 mg kg(-1) body wt), aprotinin (20,000 kIU kg(-1) body wt) and melatonin (10 mg kg(-1) body wt), respectively. The animals were killed on the sixth day. The average thickness of the retina and inner plexiform layer for each eye was measured in sagittal section near the optic nerve and expressed in microns. The thickness of the retina and inner plexiform layer in the control group was significantly (p < 0.01) lower than in the group EU as compared with the group EU plus vitamin C, group EU plus aprotinin, group EU plus melatonin (p < 0.05). The thicknesses of the retina and inner plexiform layer in group EU plus vitamin C, group EU plus aprotinin and group EU plus melatonin were significantly (p < 0.01) lower than that in the group EU. The difference in thickness of the retina and inner plexiform layer among the groups 3, 4 and 5 was not significant (p > 0.05). In conclusion, this study demonstrated that oedematous effects of EU on the retina were reduced by the administration of intraperitoneal vitamin C, aprotinin and melatonin, i.e. these antioxidants had significant protective effects on the retina of guinea pigs against oedematous damage in EU. However, the reductive effect of vitamin C on EU was greater than that of aprotinin and melatonin. The intraperitoneal vitamin C, aprotinin and melatonin supplementations may strengthen the antioxidant defence system because of decreased ROS, and these agents may play a role in treating uveitis.

Detection of mitochondrial electron chain carrier redox status by transhepatic light intensity during rat liver reperfusion

The aim of the study was to investigate mitochondrial electron transfer during rat liver reperfusion after cold storage and hypothermic machine perfusion. Livers from male Brown Norway rats were preserved (UW) for 10 h either by cold storage (CS) or by hypothermic oxygenated perfusion extracorporal (HOPE). Transhepatic photometric analysis allowed determination of the redox status of mitochondrial cytochromes during preservation, rewarming and reperfusion. Mitochondrial electron chain carriers were inhibited at different sites with rotenone and cyanide in some experiments. reversed transcriptional polymerase chain reaction (RT-PCR) was performed after reperfusion concerning transcription of TNFα, caspase 9, and c-jun kinase (JNK). Increased superoxide anion formation as well as transcription of TNFα, caspase 9, and JNK during reperfusion after cold storage (CS) were related with completely reduced cytochromes before and during reperfusion. In contrast, hypothermic oxygenated livers (HOPE) showed oxygenated cytochromes as well as decreased superoxide anion formation and no detectable transcription of TNFα, caspase 9, and JNK. A similar low level of superoxide anion formation was found when electron chain transfer of cold stored livers was inhibited during reperfusion with rotenone but not with cyanide. After hypothermic oxygenation (HOPE) inhibition of mitochondrial electron chain with rotenone showed no change in formation of superoxide anion formation whereas inhibition with cyanide showed increased superoxide anion formation. Thus mitochondrial cytochrome redox status is suggested to be related: (i) with the release of reactive oxygen substances as well as (ii) with the expressions of TNFα, caspase 9, and JNK during reperfusion and may thus be usable as predictive marker of liver grafts.

Cellular damage to human hepatocytes through repeated application of 5-aminolevulinic acid

Background/Aims: 5-Aminolevulinic acid (ALA), a precursor of porphyrins is used for photodynamic diagnosis and therapy within topical or systemic applications. A potential toxic effect on the human liver is of major interest and therefore we investigated the impact of a repeated application of ALA without illumination on cultures of human hepatocytes. Methods: After ALA treatment of hepatocytes in vitro the porphyrin synthesis, albumin secretion, liver-specific enzyme release, and malondialdehyde levels were determined. In order to reduce levels of reactive oxygen substances, mannitol and the antioxidant enzymes superoxide dismutase and catalase were supplemented. Results: Porphyrin biosynthesis by human hepatocytes in vitro was repeatedly stimulated by ALA (0.001–1.0 mM), which was indicated by an accumulation of protoporphyrin IX. A repetitive treatment (up to four times) of hepatocytes with ALA resulted in an impairment of the hepatic function and viability, depending on the ALA concentration (0.1–1.0 mM) and frequency of application (2–3 times). This was also accompanied by increased malondialdehyde levels indicating enhanced lipid peroxidation. Only superoxide dismutase was able to reduce cellular damage and prevent specific function. Conclusions: Repeated, not single, ALA treatment without illumination may cause deleterious effects to the liver, which are mediated by oxygen radicals and inhibited by an antioxidant.

Enhanced testicular antioxidant capacity in streptozotocin-induced diabetic rats: protective role of vitamins C and E and selenium.

Diabetes mellitus is associated with diabetic impairment of testicular function, ultimately leading to reduced fertility. Its etiology may involve oxidative damage by reactive oxygen substances, and protection against this damage can be offered by antioxidant supplementation. The aim of this study was to investigate the effects of intraperitoneal administration of vitamin C and E, selenium (Se), and vitamin E plus Se (COM) on concentrations of lipid peroxide (as malondialdehyde; MDA), reduced glutathione (GSH), and vitamin E concentrations and glutathione peroxidase (GSH-Px) activity in the testes of rats with diabetes induced by streptozotocin (STZ). Sixty groups were used (10 animals each) and these animals were initially allocated to two groups: control group and diabetic group. The diabetic group was subdivided into five groups as follows: diabetic control (DC), vitamin E, Se, COM, and vitamin C. Animals in the DC group and vitamin C, vitamin E, Se, and COM groups were made diabetic by the injection of STZ on 4 d after an injection of vitamins C and E, Se, and COM. Those vitamins and Se were also administered for 21 consecutive days. The MDA, vitamin E, GSH levels, and GSH-Px activities in testes were determined. Although the vitamin E concentration was higher in the control than in the DC group, the MDA levels were found to be lower in the control than in the DC group. The MDA levels in the testes samples of vitamin C, vitamin E, Se, and COM groups were lower than the DC group. However, GSH-Px activity and GSH levels in the testes were not significantly different between the control and DC groups. Vitamin E concentrations in the vitamin C, vitamin E, Se, and COM groups and GSH levels and GSH-Px activities in the Se, COM, and vitamin C groups were higher than either the control or DC group. The results indicate that reactive oxygen substances may be involved in possible testicular complications in diabetes of rats. Administration of vitamins C and E and Se reduced the testicular lipid peroxidation; these vitamins and Se had significant protective effects on testes of rats against oxidative damage in diabetes.

Sulfur Mustard Intoxication, Oxidative Stress, and Antioxidants

Sulfur Mustard (SM) is a potent alkylating agent with electrophilic property which has been used as a chemical warfare agent in at least 12 conflicts. It has reemerged as a major threat in recent years. Medical attention is primarily concerned with its action on the skin, eyes, and respiratory tract which may be complicated by damage to ophthalmic, pulmonary, and gasterointestinal systems, followed by bone marrow depression. The cytotoxicity of SM and production of reactive oxygen substances (ROS) has been proposed to result from electrophilic or oxidative stress with depletion of cellular detoxifying thiol levels including glutathione. Also, ROS are transformed by iron-requiring reactions into highly toxic oxidants that cause a chain reaction with membrane phospholipids to form lipid peroxides, leading to loss of membrane function, membrane fluidity, and finally membrane integrity. Provision and availability of scavengers of ROS and electrophilic compounds such as glutathione, sulfhydryls compounds, antioxidants, and substances that will increase production of endogenous scavengers may be considered protective and useful. Thereby, the role of substances such as selenium, copper, zinc, and antioxidants including vitamin E, vitamin C, and compounds like beta-carotene against SM cytotoxicity and lipid peroxidation might be interesting to be investigated in experimental animal models.

Meeting report: mechanisms of cell death 2000.

“Truth does not become more true by virtue of the fact that the entire world agrees with it, nor less so even if the whole world disagrees with it” (Maimonides). This quotation best expresses the theme of the third biennial meeting of the International Cell Death Society held on May 6, 2000 in Escorial, Spain. The meeting entitled “Mechanisms of Cell Death,” organized by Zahra Zakeri, Richard A. Lockshin, and Carlos Martinez-A. It filled to capacity with over 300 participants. The speakers included both junior (55%) and senior (45%) scientists with 42% women. The broad perspective covered six sections: Development and Aging; Extracellular Signaling; Cell Death in Disease; Cellular Signaling; Cell Survival; and Proteolysis, ending with a workshop on phagocytosis. In this meeting many of the speakers either challenged ideas that recently dominated the field, or elaborated and nuanced ideas that previously were considered to be straightforward. For instance, initiation of cell death remains as complex a question as ever. Numerous promoter sites for the Drosophila gene reaper indicate very complex regulation (Abrams). In AIDS, there is a complex balance between host-driven pro-apoptotic and virus-driven antiapoptotic forces (Cossarizza) and a dysregulation of cytokines (Gougeon). The role of mitochondria in apoptosis was addressed at several levels. Kroemer demonstrated that Bcl2 could inhibit a liposome-embedded Permeability Transition Pore Complex. Martinou considered that Bax can release cytochrome c but also can act by a secondary mechanism. It was reported that at the cellular level Bcl2 and bax differed in their capacities to localize to different compartments, indicating that their behavior and hence functions in intact cells may differ from strictly biochemical measurements in vitro (Borner). Physical, autophagic, loss of mitochondria was argued by Tolkovsky as a death commitment point. Depolarization of only a subset of mitochondria could initiate the apoptotic program. (D’Herde). An intriguing change of view was reflected in the mode of activation and function of the caspases, and the relationship of caspase-dependent to caspase-independent death. Several researchers suggested functions other than apoptosis for caspases. Hardwick found that proteolysis converted anti-apoptotic proteins into pro-apoptotic proteins, thus guaranteeing the launching of apoptosis. Roy contended that the dormancy of caspases is controlled by a DDD (Asp-Asp-Asp) “safety catch” sequence in caspases. Caspase 8 was shown to correlate inversely with tumor radiosensitivity (Zhivotovsky). FLIP inhibits casp8 (Thome) and HSP72 blocks casp3 activation (Anderson). Jaatella reported the intriguing finding that depletion of HSP70 (by antisense mRNA) activated a tumor-specific death program that was independent of caspases and bypassed bcl-2. Evidence was presented for the function of caspases in roles other than in cell death. Apaf1 and caspase 9 are important in tumor development (Soengas). Woo, looking at casp3 knockouts, demonstrated a role for casp3 in proliferation, perhaps by downregulating p21. Silke, using a novel screen in yeast, found that XIAPs inhibit UV-induced apoptosis, a surprising finding because they were supposed to act at a far downstream point. Other proteases such as matrix metaloproteinases and stromelysin were posited to be an extremely important part of autophagic death in tadpole metamorphosis (Shi; also noted by Linden) and granzyme B can produce reactive oxygen substances and ψm without the participation of caspases (Greenberg). More evidence for the involvement of other proteases was presented by Torriglia, who showed that, in lens, cleavage of leukocyte elastase inhibitor (LEI) achieved a double purpose: it relieved inhibition of a serine protease; and it turned LEI into L-DNase II, which is involved in degradation of the DNA. Roberg found that, in oxidative stress-induced apoptosis, lysosomal destabilization preceded mitochondrial changes, and pepstatin, an inhibitor of cathepsin D, blocked progress of apoptosis. Bursch, arguing that autophagic death differed from chemical apoptosis, emphasized that autophagic death requires ATP, is specific for elimination of different types of organelles, and requires extensive involvement of the cytoskeleton. The meeting was one of the first to emphasize phagocytosis, both in the primary meeting and in the following

A NOVEL HYDROXYL RADICAL SCAVENGER, NICARAVEN, ATTENUATES ISCHEMIA REPERFUSION INJURY OF THE LIVER

278 Protection of the liver against ischemia and reperfusion (R/I) injury is essential to achieve satisfactory outcome after liver transplantation. Although various factors have been proposed to explain hepatic R/I injury, reactive oxygen substance of the cellular membrane and such cellular components has been considered and to play a crucial role. But enhancement of the defense system by supplementation of various antioxidants has been applied, it has only limited effect due to small range of biological activity and/or restricted distribution of each agents in the biological system. Nicarven (AVS) is a novel hydroxyl radical (• OH) scavenger which has both hydrophilic and lipophilic property and permeates evenly into cellular and extracellular space. Using two-hour total hepatic vascular exclusion model in dogs, we tested our hypothesis that the administration of a novel •OH scavenger would attenuate I/R injury of the liver. After skeltonization, the liver was made totally ischemic for 2 hours by cross-clamping the portal vein, the hepatic artery, and the vena cava (above and below the liver). Veno-venous bypass was used to decompress splancnic and inferior systemic venous congestion. Seventeen beagle dogs were divided into two groups 6 animals treated with AVS (Group A), and 11 with no treatment(Group C). AVS was administered intravenously at a rate of 2mg/kg/min for 60 minutes before ischemia and 3 hours after reperfusion. Animal survival, hepatic tissue blood flow (HTBF), tissue high energy phosphate level and liver enzymes level were determined. Histopathologically, severity of sinusoidal and parenchymal damages, and the number of infiltrated polymorphonuclear cells in the postischemic liver tissue were analyzed. AVS allowed survival of the all animals (6/6, 100%), while only 3 control animals lived for 2 weeks (3/11,27%p<0.01). In addition, treatment remarkably augmented HTBF and reduced hepatocyte injury. Any adverse effect was not observed in the animals treated with AVS.FigureIschemia and reperfusion injury of the liver was markedly attenuated by AVS, indicating it as a promising agent for improved presevation of hepatic graft.